Ibn ‘Umar said God’s Messenger prohibited shighar, which means that a man gives his daughter in marriage on condition that the other gives his daughter to him in marriage without any dower being paid by either. In a version by Muslim he said, “There is no shighar in Islam."
He reported God’s Messenger as saying, “A woman must not ask to have her sister* divorced in order to deprive her of what belongs to her, but she must marry, because she will have what has been decreed for her."
(Bukhari and Muslim.)
* The word ‘sister’ is here used in a general sense. The tradition has been explained as referring to one of a man’s wives trying to get him to divorce another, but it probably refers to a woman whom the man has asked in marriage wanting him to divorce his wife before she marries him.
Abu Huraira reported God’s Messenger as saying, “A man must 'not ask a woman in marriage when his brother has done so already, until he marries or gives her up."
